I am posting for a colleague who I am working with who has having a bit of trouble figuring out if he needs a visa or not.

We have a client in Switzerland we may need to do some work with.

He is an Indian national, resident in the UK on a company-sponsored work permit and already has an EU/Schengen visitor visa that is valid for a year.

We will have to go to Switzerland every now Monday, returning back to London on the Thursday and do this every week for November and December.

Is the Schengen visa he has enough, or does he need to get a special Swiss visa?

And will it cause him issues at the Swiss border if he is flying in every Monday to Thurs for this period, or are the Swiss used to this?